Flame retardant additive of fluoropolymers in flame retardants

ABSTRACT

The problem of lack of uniform dispersion of a fluoropolymer as a flame retardant additive to thermoplastic resins is solved by a dispersion of a fluoropolymer in a flame retardant which is then blended as particles with a thermoplastic resin in molten form. Furthermore, flame retardant precursors are reacted in the presence of a fluoropolymer to form a molten flame retardant mixed with the fluoropolymer in another aspect.

FIELD OF THE INVENTION

This invention relates to a process for dispersing fine solid additivesin mixtures with synthetic, thermoplastic, polymer and to productsprepared therewith. More specifically, the present invention relates toa process for dispersing a poly (tetrafluorethylene) solid additive intoa flame retarded thermoplastic resin and to products prepared thereby.

BACKGROUND OF THE INVENTION

Thermoplastic resins are used in many applications such as household,building industry, automotives and electricity, which require a highdegree of flame retardation. According to one of the most commonstandards used in the industry, namely Underwriters Laboratory (UL) 94V0, the plastics are required not to develop, during combustion,dripping, which may contribute to the spreading of fire to othermaterials.

The use of fluoropolymers, particularly the addition of poly(tetrafluoroethylene) (PTFE) fine powder to a flame retardant system isan effective way to prevent the flame dripping of many thermoplasticmaterials.

It is known in the art to prepare homogeneous mixtures of syntheticpolymeric resins with a wide variety of solid phase additives. However,the addition of PTFE fine powder to thermoplastic resins meets withdifficulties since the PTFE powder has poor flowability and tends tofibrillate when subjected to even low shear forces. The fibrillatedpowder blocks the flow of the powder in the mixer or the extruder'sfeeder and results in low quality compounds with poor dispersion of thePTFE, poor appearance and reduced contribution to flame retardancy.These drawbacks are known and the art has attempted to overcome them.

Representative of prior art processes is that described in U.S. Pat. No.4,649,168. Accordingly to this patent particles of PTFE are dispersed inaromatic polycarbonate resin-based molding compositions. The dispersionis carried out, in brief, by admixture of aqueous emulsions of the twocomponents followed by coagulation of the emulsion mixture. Coagulationmay be carried out by spray-drying, freeze-drying or the addition ofinorganic or organic salts, acids, bases or organic solvents which aremiscible with water. The process results in fine dispersions of the PTFEin the polycarbonate resin, but the degree of dispersion is dependentupon a number of variables, which require close control.

Other methods to improve the dispersion of PTFE in thermoplastic resinsare known in the art.

U.S. Pat. No. 4,753,994 discloses a process for incorporating afluoropolymer in polycarbonate compositions, comprising adding anaqueous dispersion of a fluoropolymer to a polycarbonate solution,agitating the mixture thus formed, adding a precipitation agent to causeco-precipitation of the polycarbonate and said fluoropolymer, filteringthe co-precipitate, washing and drying the filtrate.

U.S. Pat. Nos. 5,521,230 and 6,469,072 disclose a method for dispersingsolid forms of additives in polymers, which involves adding dispersionsor solutions of additive(s) to a solution of polymer in a tubular mixer(preferably in the presence of a stationary mixer). The mixer leads to asteam precipitation step, wherein all fluid ingredients in the mixtureare volatilized leaving the solid additive and resin in the desiredratio.

Molded parts prepared from the compositions of the U.S. Pat. No.4,753,994 are characterized by an improved homogeneity and flameretardancy. The process described in U.S. Pat. Nos. 5,521,230 and6,469,072 preserves the physical properties of thermoplastic polymermatrix to which the additives described therein have been added, thanksto the uniform dispersion of said additives in said polymer matrix.However, all the above processes involve the use of organic solventsthat need to be removed from the final product by evaporation, andtherefore are expensive and highly specialized.

U.S. Pat. No. 4,579,906 discloses a process for making ABS moldingmaterials by mixing an aqueous dispersion of PTFE powder, stabilizedwith an ethoxylated nonyl phenol surfactant, with a latex of one or moregraft polymers (“graft rubbers”) or a latex of one or more matrix resins(“SAN”) or a latex mixture of both, and coagulating the polymer mixture,or optionally mixing said mixture with further graft polymer and/ormatrix resin and with inorganic synergists for improving flameproofingand organic halogen compounds.

U.S. Pat. No. 6,040,370 relates to the use of fluoropolymers asadditives in thermoplastic resin compositions and, more particularly, astabilized aqueous fluoropolymer dispersion which includes afluoropolymer and a fatty acid salt, and to a method for making athermoplastic resin composition comprising a fluoropolymer additive. Thefluoropolymer additive is made by combining an aqueous fluoropolymerdispersion with a second polymer, particularly a styrene-acrylonitrileresin, and precipitating and drying the resulting combination.

EP 0550204 describes polyphenylene ether flame-retarded resins whichhave been rendered non-dripping through the inclusion of adrip-inhibiting amount of high molecular weight polyethylene resin. Itdiscusses prior art that achieves non-dripping through the use ofpolytetrafluoroethylene, which however is said to be extremely costlyand difficult to blend with polyphenylene ether resins.

EP 0861856 describes the preparation of PTFE powder that is moreflowable. However, the preparation is made in a highly specializedequipment and the flow of the powder is not as good as desired.

However, prior art methods present several drawbacks. The use ofethoxylated nonyl phenol surfactants is under scrutiny from theperspective of environmental safety, and alternative approaches tostabilizing aqueous fluoropolymer dispersions are highly desirable.Co-coagulated fluoropolymer-thermoplastic resin compositions tend to bevery difficult to handle due to clumping and poor flowability and it iscorrespondingly difficult to incorporate such additives uniformly andreproducibly into a thermoplastic resin composition. Non-uniformdistribution of fluoropolymer additive within a thermoplastic resincomposition may result in, e.g., surface imperfections, such as e.g.,streaking and splay, and in inconsistent combustion performance, suchas, e.g., uneven shrink rates and dripping.

In industrial manufacturing, economy, productivity and workingefficiency must be taken into consideration. Even though the prior artimproves some aspects related to the dispersion of conventionalpolytetrafluoroethylene in mixtures with synthetic, thermoplastic,polymer, it does not overcome the aforementioned drawbacks, leading toless economical and productive processes than desired. Moreover, PTFEconcentrates in powder form, produced according to the prior art, tendto segregate from dry blended mixtures of flame retardants and/or resinsand/or plastic additives.

A fluoropolymer-thermoplastic resin additive, that is in the form of afree-flowing powder, would be highly desirable from both the perspectiveof material handling and improving the uniformity and reproducibility ofthe thermoplastic resin compositions made therefrom.

It is therefore an object of this invention to provide an economic andefficient process for introducing a fluoropolymer into a flame retardedthermoplastic resin and evenly disperse it throughout the polymer.

It is another object of this invention to provide a fluoropolymerconcentrate that is easily compounded with a base thermoplastic resin.

It is a further object of this invention to provide a thermoplasticresin composition that is flame retarded and includes anti-drippingagent—that is free from the defects of known such compositions, inparticular is free from surface imperfections and inconsistentcombustion performance.

It is a still further object of this invention to provide a process forimproving the PTFE fine powders flowability when they are dispersed asadditive into thermoplastic resins.

It is a still further object of the present invention to provide anantidripping agent having excellent handling characteristics anddispersibility while maintaining antidripping property, as well as flameretardant resin compositions containing the antidripping agent.

Other objects and advantages of the invention will become apparent asthe description proceeds.

SUMMARY OF THE INVENTION

The present invention provides a process for preparing a flame retardedthermoplastic resin which contains a fluoropolymer anti-dripping agentwhich is evenly dispersed throughout the thermoplastic resin. Saidprocess comprises the preparation of a fluoropolymer concentrate bydispersing a fluoropolymer powder in a low viscosity melt of flameretardant(s) or flame retardant precursor(s). The fluoropolymerconcentrate is then added to the resin during the compounding stage. Ifdesired, other additives can be added to the thermoplastic resin(hereinafter also called “base resin” or “resin matrix”) in thecompounding or molding stages. Since said fluoropolymer is preferablyPTFE, this latter will be referred to throughout the presentspecification, but this should not be construed as a limitation. Saidfluoropolymer concentrate, as a composition, is one of the aspects ofthe invention.

The fluoropolymer concentrate could be added to the resin matrix in thecompounding stage while still in the molten condition. The concentrateis, as such, an aspect of the present invention. In the solid conditionit is formed by granules of fluoropolymer, preferably PTFE, at least amajority of which are covered with a coating of the flame retardantused. In one type of embodiment, the solidified concentrate is obtainedas a bulk block, which is reduced into coarse powder by the use of asuitable apparatus, e.g. a granulator or grinder provided with rotatingand stationary knives that cut the bulk block into a coarse powder.

The flame retardant(s) or flame retardant precursor(s) used should bemeltable and have a melt viscosity such that it may be easily mixed in aconventional mixer, and should have such melt viscosity at a temperatureat which it is stable, at least for the time required to mix it with thePTFE. Desirably, said melt viscosity should be below 10000 cp,preferably below 2000 cp. Preferably, the mixing temperatures are from50° C. to 300° C. Preferably, the flame retardants have a melting pointbelow 300° C., and more preferably are obtained from precursors having amelting point below 300° C.

Preferred examples of flame retardants are brominated epoxy resins, highmolecular weight brominated epoxy resins, modified brominated epoxyresins (e.g., tribromophenol modified medium molecular weight brominatedepoxy resin), low molecular weight brominated epoxy resins,tetrabromobisphenol bis(2,3-dibromopropyl ether) (e.g. produced byDSBG), partly end-capped brominated epoxy resins with fatty acid,tris(tribromophenyl)triazine (e.g. FR-245 produced by DSBG),bromophenyltrimethylindane (e.g. FR-1808 produced by DSBG), brominatedpolyacrylate, brominated polycarbonate, phenoxy-terminated carbonateoligomer of tetrabromobisphenol A and related, polypentabromobenzylacrylate (e.g. FR-1025 produced by DSBG), brominated acrylate monomer(e.g. FR-1025M produced by DSBG), brominated styrene and their homo- andco-polymers, tetrabromobisphenol A, brominated diphenylethane,decabromodiphenyl oxide, alkyl-phosphinic acid salts,tris(tribromoneopentyl)phosphate (e.g. FR-370 produced by DSBG),phosphate esters, phosphonate esters, and their mixtures.

By “flame retardant precursors” is meant herein compounds that react,generally in the presence of a catalyst, to form the desired flameretardant. When the flame retardant is a high molecular weightbrominated epoxy resin, the preferred precursors are low molecularweight (MW) brominated epoxy, brominated epoxy oligomer andtetrabromobisphenol-A. When the flame retardants are polymeric orcopolymeric, their precursors are their respective monomers or monomermixtures. In general, what precursors may or should be used to make agiven flame retardant, is known to skilled persons.

Various types of PTFE are available on the market and some of them willbe cited hereinafter. The PTFE content in the concentrate is from 0.1 to60 wt %. The amount of concentrate that is compounded with the matrixresin is from 0.01 to 35 wt %. The PTFE is used, in the process of theinvention, in particulate or powder form, wherein the particles orgranules have linear dimensions from 5 to 1000 μm.

The matrix resin may be any known thermoplastic resin, and typicalexamples are polystyrene, impact polystyrene, styrene copolymers,acrylonitrile butadiene styrene terpolymers (ABS), alloys of ABS such aspolycarbonate/ABS, alloys of polystyrene such as polyphenyleneoxide/polystyrene, polycarbonates, polycarbonate alloys with PBT orpolyamide, polyesters such as polybutylene terephthalate (PBT) andpolyethylene terephthalate (PET), polyamide resins such as polyamide 6and 66, styrene acrylonitrile copolymer (SAN), polyphenylene ether(PPE), polyester carbonate and blends of the aforesaid polymers.

Suitable fluoropolymers include homopolymers and copolymers thatcomprise repeating units derived from one or more fluorinated alphaolefin monomers. The term “fluorinated alpha olefin monomer” means analpha olefin monomer that includes at least one fluorine atomsubstituent. Suitable fluoropolymers includepoly(tetrafluoroethylene)homopolymer (PTFE), poly(hexafluoroethylene),poly(tetrafluoroethylene-hexafluoroethylene), and poly(tetrafluoroethylene-ethylene-propylene).

The composition of the invention, viz. the fluoropolymer concentrate ashereinbefore defined, may further comprise additional additives such asultraviolet and light stabilizers, UV screeners, UV absorbers, releaseagents, lubricants, colorants, plasticizers, fillers, blowing agents,heat stabilizers, antioxidants, reinforcement additives (e.g. fillers),impact modifiers, and processing aids.

The invention further comprises a process for making a composition, viz.a fluoropolymer concentrate, as described hereinbefore, which processcomprises melting a flame retardant, mixing the fluoropolymer with saidmolten flame retardant, allowing the mixture to solidify andparticulating the solidified mixture. Preferably said process comprisesproviding flame retardant precursors in molten condition, mixing saidprecursors with a fluoropolymer and optionally with a catalyst, reactingsaid precursors to form a molten flame retardant mixed with saidfluoropolymer, allowing the mixture to solidify and particulating thesolidified mixture.

As hereinbefore set forth, the fluoropolymer concentrate can be added tothe resin matrix in the compounding stage while still in the moltencondition. The compounding may be carried out in an apparatus selectedfrom the group consisting of extruders, batch mixers and internalmixers.

Plastic articles can be made by extruding or molding flame retardedthermoplastic resin of the invention, and such articles are comprised inthe invention.

The invention further comprises a master batch containing fluoropolymersdispersed in flame retardants in a plastic carrier.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

All the above and other characteristics and advantages of the inventionwill be better understood through the following illustrative andnon-limitative examples.

Preparation of the PTFE Concentrate

For the preparation of the concentrate, the flame retardant, or flameretardant precursors or their mixtures, are melted and the PTFE is mixedwith it under stirring and with whatever heating is needed to maintainthe mixture in the molten state. Thereafter it is allowed to solidify.The PTFE can be added to a mixture containing Low Molecular Weight (MW)epoxy resin, TBBA and a catalyst. This mixture reacts exothermallycausing simultaneous rise of temperature, MW and viscosity. The PTFE istrapped in the viscous liquid that solidifies on cooling, forming a bulkblock and finally said block is granulated by a suitable granulator.Alternatively, the flame retardant precursor compounds and a desiredcatalyst, if any, are mixed gradually, while being heated to form amolten phase, and the PTFE is mixed with them together with at least thelast precursor, and the precursors are reacted together to form theflame retardant in the presence of the PTFE.

The materials used in the examples are detailed in Table 1.

TABLE 1 Materials used Trade Name (Producer) General informationFunction YDB-400 Low MW brominated epoxy Reactant ex Tohto oligomer TBBATetrabromobisphenol-A Reactant ex DSBG TBP ex DSBG TriBromo PhenolReactant TBPBr (10%) Tetrabutylphosphonium bromide Catalyst ex DSBG (10%in F-2001) FR-720 ex DSBG Tetrabromobisphenol bis Flame(2,3-dibromopropyl ether) Retardant FR-245 ex DSBGTris(tribromophenyl)triazine Flame Retardant F-3020 ex DSBG Endcappedbrominated epoxy Flame oligomer (MW 2,000) Retardant F-2400 ex DSBGBrominated epoxy oligomer Flame MW: 50000 Retardant FR-1025 Ex.Poly(pentabromobenzyl acrylate) Flame DSBG Retardant AO 112 ex KafritMaster batch containing 80% FR-synergist antimony trioxide and 20%styrenic carrier AO M-0112 ex Master batch containing 80% FR-synergistKafrit antimony trioxide and 20% acrylate carrier PTFE 6-CN ex PTFE(500-600 micron) Anti-dripping Du Pont agent Hostaflon 9202 ex PTFE (5micron) Anti-dripping Dyneon agent Hostaflon 2071 ex PTFE (500 micron)Anti-dripping Dyneon agent Blendex 449 ex 50% PTFE encapsulated inStyrene Anti-dripping General Electric Acrylonitrile Copolymer agentSpecialty Chemicals 10% PTFE 6-CN Experimental PTFE 6-CN masterAnti-dripping masterbatch batch (10% PTFE, F-2400 carrier) agentconcentrate in F- 2400 ex Kafrit ABS Magnum Acrylonitrile butadienestyrene Plastic Matrix 3404 ex Dow terpolymer, general purpose gradeLexan 141 ex GE Polycarbonate Resin Multi purpose Plastic MatrixPlastics grade (MFI = 14.4 g/10 min.) PBT Celanex Poly(butyleneterephthalate) Plastic Matrix 2002-2 Ex Ticona non-reinforced PBTIrganox B-225 ex Blend of Irganox 1010 and Heat stabilizer/ Ciba Irgafos168 antioxidant Irganox B-900 ex Blend of Irganox-1010 and Heatstabilizer/ Ciba Irgafos 168 antioxidant

Example 1

4% PTFE (polytetrafluoroethylene) concentrates in high molecular weightbrominated epoxy resin flame retardant, were prepared using PTFE 6-CN exDu-Pont and PTFE Hostaflon 9202 ex Dyneon. For preparing the highmolecular weight brominated epoxy resin flame retardant PTFEconcentrate, low molecular weight (MW) brominated epoxy oligomer YDB-400was placed in a beaker and the beaker was placed in a circulated airoven at 170° C. for 3 hours. A high-speed mixer was placed in the beakercontaining the melted brominated epoxy at 150° C. and was started at3600 rpm. TBBA and TBPBr (catalyst) were added while mixing, and themelt temperature was reduced to 125° C. The temperature increasedexothermally and when it reached 135° C., PTFE was added, the melttemperature was reduced to 132° C. and the mixing speed was increased to5500 rpm. The temperature increased and when it reached 150° C. theliquid mixture was transferred into an aluminum mold and placed in acirculated air oven at 170° C. for 4.5 hours. The resulting productblock was cooled and granulated into a coarse powder using a granulatorex Rapid. The granulator is made from rotating and stationary knivesthat cut the block into a coarse powder that is passed through a 4 mmscreen.

The samples composition and analytical results are shown in Table 2.

TABLE 2 Composition and analysis of PTFE concentrates Sample number 1 2YDB 400, grams 609.2 609.2 TBBA, grams 387.6 387.6 PTFE 6-CN, grams 42Hostaflon 9202, grams 42 TBPBr (10%), grams 2 2 Chemical Properties MW(weight average molecular 33800 33400 weight) by GPC (Gel permeationchromatograph) GPC MN (Number average 8500 8300 molecular weight) ColorApha according to ASTM 304 Turbid Solution D-2108/97 (Not Filtered)Color Gardner according to 5.4 Turbid Solution ASTM D-1544 (NotFiltered) AN 0.37 0.53 AN means acid number expressed in mg KOH/gr

Example 2

6% and 12% PTFE concentrates in tribromophenol modified medium molecularweight brominated epoxy resin flame retardant were prepared using threedifferent kinds of PTFE: PTFE 6-CN ex Du-Pont, PTFE Hostaflon 2071 exDyneon and PTFE Hostaflon 9202 ex Dyneon.

The amounts of chemicals used in this example are given below in Table3. For preparing the PTFE concentrate in tribromophenol modified mediummolecular weight brominated epoxy resin, YDB-400 was placed in a beakerand the beaker was placed in a circulated air oven at 170° C. After 3hours, when the temperature reached 150° C., a high-speed mixer wasplaced in the beaker and started at 3600 rpm. TBBA and TBPBr 10%(catalyst) were added while mixing, and then the melt temperature wasreduced to 110° C. The temperature increased exothermally and when itreached 145° C., and while maintaining the mixing, TBP was added. Thetemperature increased and when it reached 150° C., PTFE was added, thenthe melt temperature was reduced to 148° C. and the mixing speed wasincreased to 5500 rpm. The temperature increased exothermally and whenit reached 155° C., the reaction mixture was transferred into analuminum mold and placed in a circulated air oven at 165° C. for 4hours. The resulting product block was cooled and granulated to a coarsepowder using a granulator ex Rapid. In Table 3 the samples compositionand analytical results achieved in this example are shown.

TABLE 3 Composition and analysis of PTFE concentrates Sample number 3 45 6 7 YDB 400, grams 1192.4 1192.4 1192.4 298.1 596.6 TBBA, grams 706706 706 176.5 353 TBP, grams 101.2 101.2 101.2 25.3 50.6 PTFE 6-CN, — —133.2 66.6 — grams Hostaflon 9202, 133.2 266.4 — — — grams Hostaflon2071, — — — — 133.2 grams TBPBr (10%), 4 4 4 1 2 grams Resulting wt % 612 6 12 12 PTFE (calculated) Chemical Analysis GPC MW 19229 18400 1961316325 16405 GPC MN 4843 8066 7292 6468 6427 Color Apha 60 78 98 87 63(Filtered) AN 0.2 0.17 0.15 0.65 0.5

Example 3

A PTFE concentrate in FR-720 flame retardant was prepared, weighing 340g of FR-720 in a 1000-ml glass beaker, which subsequently was placed ina circulated air oven at 170° C. for 3 hours. A high-speed mixer wasplaced in the beaker containing the melted FR-720, and mixing at 3600rpm was started. During the mixing, 30 g of PTFE (Hostaflon 2071) wereadded, the melt temperature was reduced to 128° C., and the rotationspeed was increased to 8000 rpm. After 2 minutes of rotation the liquidmixture was transferred into an aluminum mold. A solid homogeneousmixture was obtained. The solid mixture was ground manually, and a whitepowder was obtained.

Example 4

With the objective to evaluate PTFE concentrate in FR-1025 in flameretarded (FR) PBT formulations, an experimental work was performed. Inthis work, FR-1025M was polymerized in the presence of 10% PTFE 6-CN.

The materials used in this experiment are detailed in Table 1. Thefollowing is a description of the procedure performed.

Extrusion polymerization was performed in Berstorff ZE-25 co-rotatingtwin-screw extruder L\D=32 with open vent at zone 7. Feeding wasperformed by gravimetric feeding system K-SFS24 ex. K-Tron. FR-1025M andPTFE powder were mixed manually in a plastic bag and fed to the extrudervia the main feeding port. The polymerization went smoothly. The productobtained was a viscous melt. The concentrated melt was collected on astainless steel tray, cooled and ground by food processor. Conditions ofpolymerization are shown in Table 4 and the properties of theconcentrate obtained are shown in Table 5.

TABLE 4 Conditions of Polymerization (Berstorff ZE-25 extruder)Processing Conditions Parameters Unit Parameters ZONE 1 ° C. RT ZONE 2 °C. 190 ZONE 3 ° C. 190 ZONE 4 ° C. 190 ZONE 5 ° C. 190 ZONE 6 ° C. 190ZONE 7 ° C. 190 ZONE 8 ° C. 200 Temperature of nozzle ° C. 210 ScrewSpeed rpm 350 Feed Rate Kg/h 6 Amperage A 4 Die Pressure bar 1 MeltTemperature ° C. 185-205

TABLE 5 Properties of PTFE concentrate (Sample Number 8) Property Testmethod Value Appearance Visual An off-white free flowing powderMolecular-weight distribution GPC MN = 17800, MW = 128100 Residualmonomer FTIR Less than 1%

Example 5

A series of injection molded samples have been prepared in order toillustrate the invention. In this Example 5 are described the detailsabout the preparation of these molded samples.

The preparation and properties of the PTFE concentrates according to theinvention are given in the previous Examples 1 to 4.

All the components used for performing the compounding of all the blendswere weighed on a Sartorius semi-analytical scale. These components wereconsequently mixed manually in plastic bags and the resulting mixtureswere fed by a gravimetric feeding system, K-SFS24 ex K-Tron, directlyinto the extruder's hopper.

Compounding was performed in a twin-screw co-rotating extruder ZE25 witha length over diameter (L/D) ratio of 32 ex Berstorff. The compoundingconditions for the various plastics systems are summarized in Table 6.

There was an open vent at zone 7.

The extruded strands after cooling in water at room temperature, werepelletized in a pelletizer 750/3 ex Accrapak System Ltd. The pelletsobtained were dried in a circulating air oven ex Heraeus Instruments atthe following conditions:

For ABS: 75° C. for 4 hours.

For Poly(butylene terephthalate): 90° C. for 16 hours followed by anadditional 4 hours at 120° C.

For Polycarbonate: 120° C. for 2 hours and an additional 1 hour at 90°C.

Test specimens were prepared by injection molding in an Allrounder500-150 ex Arburg and the injection molding conditions are summarized inTable 6. All the molded specimens were conditioned before testingflammability according to the UL 94 standard (vertical condition) asfollows:

For ABS: 60 hours at 70° C.

For Poly(butylene terephthalate): 168 hours at 70° C.

For Polycarbonate: 168 hours at 70° C.

TABLE 6 Processing conditions to prepare samples for testing flameretardancy Type of plastic Poly(butylenes ABS terephthlate)Polycarbonate Compounding conditions Temperature RT*-160-230-230-RT*-220-240-255- RT*-200-220-230-230- profile, ° C. 230-230-230-230-255-265-265-265-260 230-230-230-240 230 Temperature of the 230 265 250melt ° C. Screw rotation 300 350 300 speed, rpm Injection Moldingconditions Temperature profile 180-200-230- 230-240-260-270-230-250-250-250-255 ° C. 230-230 280 Mold temperature, 40 90 110 ° C.Injection pressure, 500 1800 2200 bar Holding pressure, 250 1800 2200bar Back pressure, bar 20 45 20 Injection time, sec. 0.1 0.1 0.1 Holdingtime, sec. 10 10 10 Cooling time, sec. 5 10 8 Mold closing force, 500500 500 kN Filling volume, cm³ 21 21 21 Injection speed, 10 112 90cm¹/sec Mold reference S 22963 S 22963 S 22963 number *RT—Roomtemperature (no heating in the feeding zone)

Example 6

Compositions of flame-retarded acrylonitrile-butadiene-styrenecopolymers (ABS) were processed as described in Example 5 to prepareinjection molded bars that were tested for their fire retardancyaccording to the UL 94 standard. The flame retardant system used is acombination of FR-245 and antimony trioxide. The compositions tested andtheir flame retardancy properties are summarized in Table 7.

TABLE 7 Application of the invention in ABS flame retarded by FR-245Sample Number 9 10 11 12 PTFE No Example 2 Blendex 449 Blendexconcentrate concentrate, sample no. 5 449 type reference (6% PTFE 6-CN)Composition, wt % ABS Magnum 79.7 83.73 83.75 83.65 3404 + additivesFR-245 14.9 11.6 11.9 11.9 Antimony 5.4 4.25 4.3 4.3 trioxidemasterbatch concentrate A.O. 112 PTFE 0.00 0.42 0.05 0.15 concentrateBromine 10.0 8.0 8.0 8.0 content wt % (Calculated) PTFE content 0.0000.025 0.025 0.075 wt % (Calculated) Flame retardancy (UL 94 V, 1.6 mmthickness) Max. flaming 18 7 33 24 time, sec. Total flaming 85 35 155103 time, sec. Max. 31 25 0 77 afterglow, sec. Total 67 61 0 250afterglow, sec. Number of 3 0 5 0 dripping samples Number of 3 0 5 0cotton ignitions Class V-2 V-0 NR NR

It can be seen from the fire retardancy properties shown in Table 7 thatthe addition of a PTFE concentrate according to the invention is veryefficient, as it enables a class V-0 not only with significantly lessbromine and antimony trioxide, but also with shorter total flaming timeand no dripping at all.

Compared with a commercial PTFE concentrate available on the market suchas Blendex 449, the concentrate according to the invention is also muchmore efficient with respect to total flaming time, anti-drippingproperties and flame retardancy class, being V-0 with a minimum contentof PTFE in the final composition, while all the other examples withBlendex 449 are not rated even with three times more PTFE in the finalcomposition.

Example 7

Compositions of flame-retarded acrylonitrile-butadiene-styrenecopolymers (ABS) were processed as described in Example 5 to prepareinjection molded bars that were tested for their fire retardancyaccording to the UL 94 standard. The flame retardant system used is acombination of FR-245 and antimony trioxide. The compositions tested andtheir flame retardancy properties are summarized in Table 8.

TABLE 8 Application of the invention in ABS flame retarded by FR-245Sample Number 9 (Example 6) 13 14 PTFE concentrate type No Example 2Blendex concentrate, sample no. 5 449 reference (6% PTFE 6- CN)Composition, wt % ABS Magnum 3404 + additives 79.7 79.6 79.65 FR-24514.9 14.6 14.9 Antimony trioxide 5.4 5.38 5.4 masterbatch concentrateA.O. 112 PTFE concentrate 0.00 0.42 0.05 Bromine content 10.0 10.0 10.0wt % (Calculated) PTFE content wt % 0.000 0.025 0.025 (Calculated) Flameretardancy (UL 94 V, 1.6 mm thickness) Max. afterglow, sec. 31 19 26Total afterglow, sec. 67 45 76 Class V-2 V-0 V-0

In this example, one can see the advantages of the contribution of theuse of the PTFE concentrate prepared according to the invention: For asimilar bromine and antimony trioxide content, the molded samplescontaining it when tested according to UL 94 show much less afterglowtime than commercial grades of PTFE concentrates.

Example 8

Compositions of flame-retarded acrylonitrile-butadiene-styrenecopolymers (ABS) were processed as described in Example 5 to prepareinjection molded bars that were tested for their fire retardancyaccording to the UL 94 standard. The flame retardant system used is acombination of FR-245 and antimony trioxide. The compositions tested andtheir flame retardancy properties are summarized in Table 9.

TABLE 9 Application of the invention in ABS flame retarded by FR-245Sample Number 9 13 (Example 6) (Example 7) 15 16 PTFE concentrate NoExample 2 Example 2 Example 2 type concentrate, sample sample samplereference no. 5 no. 5 no. 5 (6% PTFE (6% PTFE (6% PTFE 6-CN) 6-CN) 6-CN)Composition, wt % ABS Magnum 79.7 79.6 79.47 79.35 3404 + additivesFR-245 14.9 14.6 14.3 14.0 Antimony trioxide 5.4 5.38 5.4 5.4masterbatch concentrate A.O. 112 PTFE concentrate 0.00 0.42 0.83 1.25Bromine content 10.0 10.0 10.0 10.0 wt % (Calculated) PTFE content wt %0.000 0.025 0.050 0.075 (Calculated) Flame retardancy (UL 94 V, 1.6 mmthickness) Total afterglow sec. 67 45 31 18 Class V-2 V-0 V-0 V-0

In this example, one can see that an increase of the loading of PTFEconcentrate according to the invention in the composition bringsadditional improvement of the fire retardancy properties by furtherreducing the total afterglow time, while the bromine and antimonytrioxide concentrate content are very similar in the formulation.

Example 9

Compositions of flame-retarded acrylonitrile-butadiene-styrenecopolymers (ABS) were processed as described in Example 5 to prepareinjection molded bars that were tested for their fire retardancyaccording to the UL 94 standard. The flame retardant system used is acombination of FR-245 and antimony trioxide. The compositions tested andtheir flame retardancy properties are summarized in Table 10.

TABLE 10 Application of the invention in ABS flame retarded by FR-245Sample Number 9 (Example 6) 17 PTFE concentrate type No concentrate,Example 2 reference sample no. 4 (12% Hostaflon 9202) Composition wt %ABS Magnum 3404 + 79.7 79.79 additives FR-245 14.9 14.4 Antimonytrioxide 5.4 5.4 masterbatch concentrate A.O. 112 PTFE concentrate 0.000.41 Bromine content wt % 10.0 10.0 (Calculated) PTFE content wt % 0.0000.050 (Calculated) Flame retardancy (UL 94 V, 1.6 mm thickness) Max.flaming time, sec. 18 7 Total flaming time, sec. 85 23 Max. afterglow,sec. 31 25 Total afterglow, sec. 67 50 Number of dripping 3 0 samplesNumber of cotton ignitions 3 0 Class V-2 V-0

In this example it is shown that a PTFE concentrate prepared accordingto the invention as described in Example 2, sample 4, that contains 12%PTFE (grade Hostaflon 9202) is also contributing to improvesignificantly the fire retardancy properties of ABS compared with thereference composition that does not contain it. Not only this PTFEconcentrate eliminates completely the dripping of the molded samplesexposed to the flame (UL 94 standard), but moreover, significantreduction in burning and afterglow times is noticed.

Example 10

Compositions of flame-retarded acrylonitrile-butadiene-styrenecopolymers (ABS) were processed as described in Example 5 to prepareinjection molded bars that were tested for their fire retardancyaccording to the UL 94 standard. The flame retardant system used is acombination of FR-245 and antimony trioxide. The compositions tested andtheir flame retardancy properties are summarized in Table 11.

TABLE 11 Application of the invention in ABS flame retarded by FR-245Sample Number 10 13 (Ex. 6) 18 (Example 7) 19 20 21 PTFE concentrateExample 2 sample no. 5(6% PTFE 6-CN) PTFE 6-CN as is:, no use type ofconcentrate reference Composition wt % ABS Magnum 83.73 81.6 79.6 83.82581.695 79.695 3404 + additives FR-245 11.6 13.1 14.6 11.9 13.4 14.9Antimony trioxide 4.25 4.88 5.38 4.25 4.88 5.38 masterbatch concentrateA.O. 112 PTFE concentrate 0.42 0.42 0.42 0.025 0.025 0.025 Brominecontent wt % 8.0 9.0 10.0 8.0 9.0 10.0 (Calculated) PTFE content wt %0.025 0.025 0.025 0.025 0.025 0.025 (Calculated) Flame retardancy (UL 94V, 1.6 mm thickness) Max. flaming time, 7 3 3 19 13 3 sec. Total flamingtime, 35 20 15 78 55 16 sec. Max. afterglow, 25 13 19 31 53 33 sec.Total afterglow, 61 35 45 37 88 40 sec. Number of dripping 0 0 0 3 1 0samples Number of cotton 0 0 0 3 1 0 ignitions Class V-0 V-0 V-0 V-2 V-2V-1

In this series of examples, a comparison is made between the use of aconcentrate according to the invention that has been described inExample 2 as sample no. 5 (using 6% PTFE 6-CN) and the use of PTFE 6-CNand its introduction in the ABS compound as is and not as a concentrate.The results in Table 11 show a clear advantage achieved by the use ofthe concentrate according to the invention in terms of class of fireretardancy, class V-0 being achieved for all the formulations while withthe use of PTFE as is they are classified V-2 or maximum V-1 with longerburning times and maximum afterglow times.

Moreover, PTFE concentrates as described in this invention have asuitable particle size and strength enabling a much easier feed in thehopper of the extruder during compounding without risking to lose someof the material on the wall of the hopper, as is the case when usingPTFE powder. The PTFE concentrates as described in this invention arealso easier to compound to get a homogeneous blend at the origin ofbetter fire retardant efficiency.

Example 11

Compositions of flame-retarded acrylonitrile-butadiene-styrenecopolymers (ABS) were processed as described in Example 5 to prepareinjection molded bars that were tested for their fire retardancyaccording to the UL 94 standard. The flame retardant system used is acombination of F-3020 and antimony trioxide. The compositions tested andtheir flame retardancy properties are summarized in Table 12.

In this series of examples, it is shown that PTFE concentrates preparedaccording to the invention are also efficient with other brominatedflame-retardants such as tribromophenyl end-capped brominated epoxyoligomers (e.g. F-3020 produced by DSBG) to improve flame retardancy byreducing significantly flaming times and by eliminating drippingsamples.

TABLE 12 Application of the invention in ABS flame retarded by F-3020Sample Number 22 23 24 PTFE concentrate type No Example 2 Example 2Concentrate, sample no. 5 sample no. 4 reference (6% PTFE 6- (12%Hostaflon CN) 9202) Composition, wt % ABS Magnum 3404 + 79.15 79.0 79.44additives F-3020 16.1 15.0 15.4 Antimony trioxide 4.75 4.75 4.75masterbatch concentrate A.O. 112 PTFE concentrate 0.0 1.25 0.41 Brominecontent wt % 9.0 9.0 9.0 (Calculated) PTFE content wt % 0.0 0.075 0.050(Calculated) Flame retardancy (UL 94 V, 1.6 mm thickness) Max. flamingtime, sec. 10 7 3 Total flaming time, sec. 38 22 13 Number of dripping 20 0 samples Number of cotton ignitions 1 0 0 Class V-2 V-0 V-0

Example 12

Compositions of non glass reinforced flame retarded polybutyleneterephthalate) (PBT) were processed as described in Example 5 to prepareinjection molded bars that were tested for their fire retardancyaccording to the UL 94 standard. The flame retardant systems used are acombination of FR-1025 or F-2400 and antimony trioxide. The compositionstested and their flame retardancy properties are summarized in Table 13.

As can be seen from samples 25 and 26, the application of the inventionin PBT fire-retarded by FR-1025 is very efficient to eliminate thedripping, reduce flaming times and reach class V-0 with the same loadingof fire retardant. Fire retardant properties of samples 27 to 30illustrate two advantages of the invention in the case of PBT fireretarded by F-2400:

1. Addition of the PTFE concentrate prepared according to the inventionas in sample 28 eliminates the dripping seen in sample 27 of the moldedsamples and enables reaching class V-0 even with the thickness of 0.8mm.2. The efficiency of the PTFE concentrate prepared according to theinvention cannot be achieved at all by the use of PTFE concentrateprepared with the same grade of PTFE by extrusion compounding followedby pelletization as in the existing practice in the plastic industry(samples 29 and 30). Even by doubling the PTFE content in theformulation, dripping is not eliminated and the molded PBT parts do notreach the more severe class V-0.

TABLE 13 Application of the invention in PBT flame retarded by FR-1025or F-2400 Sample Number 25 26 27 28 29 30 PTFE concentrate No Example 4No Example 1 10% PTFE 6-CN 10% PTFE 6-CN type concentrate, Sample 8concentrate, Sample 1 masterbatch masterbatch reference referenceconcentrate concentrate in F-2400 in F-2400 Composition, wt % PBTCelanex 2002-2 83.75 83.65 80.25 80.15 80.15 80.05 FR-1025 10 9.1 — — —— F-2400 — — 13.5 11 12.6 11.7 Antimony trioxide 6.25 6.25 6.25 6.256.25 6.25 masterbatch concentrate A.O. M-112 PTFE concentrate 0 1 0 2.51 2 Bromine content wt % 7 7 7 7 7 7 (Calculated) PTFE content wt % 00.1 0 0.1 0.1 0.2 (Calculated) Flame retardancy (UL 94 V, 1.6 mmthickness) Max. flaming time, 1 1 0 0 0 0 sec. Total flaming time, 10 50 0 0 0 sec. Number of dripping 5 0 5 0 5 5 samples Number of cotton 4 05 0 5 5 ignitions Class V-2 V-0 V-2 V-0 V-2 V-2 (thickness) (1.6 mm)(1.6 mm) (0.8 mm) (0.8 mm) (0.8 mm) (0.8 mm)

Example 13

Compositions of polycarbonate (PC) were processed as described inExample 5 to prepare injection molded bars that were tested for theirfire retardancy according to the UL 94 standard. The flame retardantsystem used is F-2400. The compositions tested and their flameretardancy properties are summarized in Table 14.

TABLE 14 Application of the invention in PC flame retarded by F-2400Sample Number 31 32 PTFE concentrate type Example 2 Blendex 449 sampleno. 6 (12% PTFE 6- CN) Composition, wt % PC Lexan 141 92.9 92.9 F-24005.2 6.7 PTFE concentrate 1.7 0.2 Bromine content wt % 3.5 3.5(Calculated) PTFE content wt % 0.1 0.1 (Calculated) Flame retardancy (UL94 V, 1.6 mm thickness) Max. flaming time, sec. 7 17 Total flaming time,sec. 28 72 Number of dripping 0 1 samples Number of cotton ignitions 0 1Class V-0 V-2 Impact properties Notched IZOD J/m 806 785

It can be seen from the fire retardancy properties shown in Table 14that the addition of a PTFE concentrate according to the invention isalso more efficient in polycarbonate as it enables a class V-0 with alow-level of bromine and without any synergist such as antimony trioxidewhile with a commercial PTFE concentrate available on the market, suchas Blendex 449, dripping is still occurring and only class V-2 isachieved. It is worthwhile to note also that better impact, an importantproperty for polycarbonate applications, is obtained with the PTFEconcentrate prepared according to the invention.

The above description and examples have been provided for the purpose ofillustration and are not intended to limit the invention in any way. Thenovel compositions of the invention may be implemented with a variety ofdifferent plastic materials, and many modifications can be carried outin the compositions and in the processes for making them, all withoutexceeding the scope of the invention.

1-13. (canceled)
 14. Process for making a composition having one or more fluoropolymers dispersed in one or more flame retardants, comprising: (i) melting the flame retardant; (ii) mixing the fluoropolymer with said molten flame retardant; (iii) allowing the mixture to solidify; and (iv) particulating the solidified mixture.
 15. Process for making a composition having one or more fluoropolymers dispersed in one or more flame retardants, which comprises providing flame retardant precursors in molten condition, mixing said precursors with the fluoropolymer and optionally with a catalyst, reacting said precursors to form a molten flame retardant mixed with said fluoropolymer, allowing the mixture to solidify and particulating the solidified mixture. 16-24. (canceled) 